Field of the Invention
The present invention relates to a starter.
Priority is claimed on Japanese Patent Application No. 2014-070221, filed Mar. 28, 2014, Japanese Patent Application No. 2014-070246, filed Mar. 28, 2014, Japanese Patent Application No. 2013-125048, filed Jun. 13, 2013, Japanese Patent Application No. 2014-070235, filed Mar. 28, 2014, Japanese Patent Application No. 2014-070508, filed Mar. 28, 2014, and Japanese Patent Application No. 2014-070379, filed Mar. 28, 2014, the contents of which are incorporated herein by reference.
Description of Related Art
For example, among starters used to start an engine of an automobile, there is a starter including a motor unit, a drive shaft, a pinion gear, a clutch mechanism, and an electromagnetic device, as major components (for example, see Japanese Unexamined Patent Application, First Publication No. H07-12034, and Japanese Unexamined Patent Application, First Publication No. 2008-240539).
The motor unit generates a rotational force by supplying electricity. A drive shaft is rotated by receiving a rotational force of the motor unit. The pinion gear is installed on a ring gear of the engine to be meshed with or separated from the ring gear to transmit the rotational force of the drive shaft to the ring gear. The clutch mechanism is installed between the drive shaft and the pinion gear to transmit or block the rotational force of the drive shaft to the pinion gear. The electromagnetic device generates a pressing force to the pinion gear toward the ring gear via the clutch mechanism. The drive shaft is rotatably supported by a housing. In addition, the electromagnetic device is received in the housing.
Here, the driving pinion gear may be slidably installed on the drive shaft, or may be slidably installed on an idle shaft extending in a direction parallel to the drive shaft according to circumstances such as layout or the like of the starter.
A so-called 2-shaft type starter having two shafts of the drive shaft and the idle shaft includes a transmission pinion gear installed on the drive shaft and an idle gear installed on the idle shaft and meshed with a transmission pinion gear. Accordingly, a rotational force of the drive shaft can be transmitted to the ring gear via the idle gear (for example, PCT International Publication No. WO2007/034666).
In addition, Japanese Unexamined Patent Application, First Publication No. 2002-130097 discloses a starter in which a ring gear and a pinion gear are configured of helical gears. The ring gear and the pinion gear have a skew direction (a helical skew direction) of gear teeth set such that a thrust load is generated in a direction from a position at which the pinion gear is withdrawn from the ring gear toward a position at which the pinion gear is meshed with the ring gear (hereinafter, the direction is appropriately referred to as a plunge direction) when the pinion gear is meshed with the ring gear.
According to the above-described configuration, in comparison with the starter in which the ring gear and the pinion gear are configured of spur gears, since a tooth contact ratio of the ring gear and the pinion gear is increased, noises due to meshing of the ring gear and the pinion gear upon start of the engine are reduced. In addition, once a distal end of the pinion gear is meshed with the ring gear upon start of the engine, since the pinion gear progresses to be suctioned into the ring gear by the thrust load, the pinion gear is likely to be meshed with the ring gear.
In addition, the electromagnetic device includes an exciting coil, a plunger holder, a switch plunger and a gear plunger. The plunger holder is installed on a push-out direction side of the driving pinion gear (pinion gear) on the exciting coil. The switch plunger has a cylindrical shape installed inside of the exciting coil in a radial direction, and is configured to be attracted and slid by a magnetic force generated by supplying electricity to the exciting coil. The gear plunger has a cylindrical shape installed further inside in the radial direction than the switch plunger, and includes an iron core attracted by a magnetic force generated due by supplying electricity to the exciting coil and slides in the axial direction.
Then, in the starter, when the electromagnetic device is supplied with electricity, the switch plunger slides in the push-out direction of the driving pinion gear by the exciting coil. Along with this, the gear plunger slides in the push-out direction of the driving pinion gear. Then, as the gear plunger slides in the push-out direction, the driving pinion gear is pushed out via the clutch mechanism. In addition, as the switch plunger slides, the motor unit is supplied with electricity, and the motor unit rotates. When the motor unit rotates, the drive shaft is rotated, and inertia is applied by further rotation of the drive shaft, and the driving pinion gear is further pushed out to be meshed with the ring gear.
When the driving pinion gear is pushed out until it meshes with the ring gear, the switch plunger and the gear plunger also slides in the push-out direction to follow the driving pinion gear. Then, positions of the switch plunger and the gear plunger are held by a magnetic attractive force of the exciting coil. Accordingly, the meshing of the ring gear and the driving pinion gear is also maintained (for example, see Japanese Unexamined Patent Application, First Publication No. 2013-130077).
In addition, for the convenience of the layout of the ring gearbased on the structure of the engine side, there may be a case in which the drive shaft of the starter attached to the engine protrudes outward from the housing in the axial direction, the driving pinion gear is installed on an end section of the protruding drive shaft, or the driving pinion gear is installed on the idle shaft extending in a direction parallel to the drive shaft and configured to receive the rotational force of the drive shaft to be rotated.
Further, when the idle shaft is installed, there may be a case in which the idle shaft protrudes outside from the housing of the starter in the axial direction, and the driving pinion gear is installed on the end section of the protruding idle shaft.
In this way, a seal member such as an oil seal or the like is installed on a hole of the housing through which the shaft is inserted, such that foreign substances such as water or the like do not intrude into the housing from the hole of the housing through which the shaft passes when the drive shaft or the idle shaft protrudes outside from the housing of the starter in the axial direction and the driving pinion gear is installed on the end section of the protruding shaft. Hereinafter, an example of the case in which the seal member is installed will be described in detail.
FIG. 42 is a view showing a seal member installed in a housing of a starter of the related art (for example, see Japanese Unexamined Patent Application, First Publication No. 2011-231671).
As shown in FIG. 42, a starter 500 includes a housing 501. An electric motor (not shown) is attached to the housing 501. In addition, in the starter 500, a drive shaft (a shaft) 502 rotated by receiving a rotational force of the electric motor (not shown) is installed. The drive shaft 502 is rotatably supported by the housing 501.
A through-hole 503 through which the drive shaft 502 is inserted is formed in the housing 501. Then, a driving gear 504 is attached to an end section 502a of the drive shaft 502 protruding outside from the housing 501 in the axial direction (a right side of FIG. 42). The driving gear 504 is meshed with or separated from a ring gear 508 as the drive shaft 502 slides.
In addition, a bearing mounting section 503a and a seal mounting section 503b disposed further outside in the axial direction than the bearing mounting section 503a and having a diameter reduced by a step difference are formed on an inner circumferential surface of the through-hole 503 of the housing 501. Then, a bearing 505 configured to rotatably support the drive shaft 502 is mounted on the bearing mounting section 503a. In addition, an oil seal 506 configured to prevent foreign substances such as water or the like from intruding into the housing 501 is mounted on the seal mounting section 503b. 
Further, an inner flange section 507 is formed on an inner circumferential surface of the through-hole 503 of the housing 501 further outside than the seal mounting section 503b (the right side of FIG. 42). The inner flange section 507, which suppress the oil seal 506 from being directly covered by water, functions as a retainer configured to prevent the oil seal 506 from falling from the housing 501.
In addition, in order to improve the meshing of the ring gear and the pinion gear, a structure that helically meshes the gears with each other may be employed. In this case, a direction of the thrust load applied to the pinion gear, which is associated with a variation in rotational speed of the ring gear due to behavior of the engine upon start of the engine, is varied based on a rotational speed difference between the pinion gear and the ring gear.
Specifically, when the rotational speed of the ring gear is lower than that of the pinion gear, a thrust load toward the ring gear is applied to the pinion gear, and the pinion gear is displaced toward the ring gear. Meanwhile, when the rotational speed of the ring gear is higher than that of the pinion gear, a thrust load toward an opposite side of the ring gear is applied to the pinion gear, and the pinion gear is displaced toward the opposite side of the ring gear.
When the rotational speed of the ring gear becomes lower than that of the pinion gear and the pinion gear is rotated by the rotational force of the motor unit, if there is a backlash between the gear plunger and the clutch mechanism, the clutch mechanism is displaced in the axial direction to an extent of the backlash. For this reason, transmission of the rotational force of the motor unit to the pinion gear is delayed slightly to that extent.
Further, since a load applied to rotation of the motor unit is also reduced while the clutch mechanism is moved to the extent of the backlash, the rotation of the motor unit is acceralating. However, when the backlash is blocked, the load is applied to the rotation of the motor unit so that the motor is shifted from accelerating to maintaining a constant speed. abnormal noiseRotational irregularities of the motor unit may occur due to variation in the rotational speed of the motors and abnormal noises may be generated due to the rotational irregularities.
Especially in an automobile having an idle stop function, since the starting of the conventional engine is performed by manipulating a key cylinder depending on a user's intention, an engine starting sound (a starter operating sound) is not particularly a problem because it performs an important function of audibly signalling that the engine is being started. However, since restarting a stopped engine is performed regardless of the user's intention upon re-departure or the like after temporary stoppage of a vehicle, the need for silence of the engine starting sound (the starter operating sound) is increased. In this way, in the vehicle having the idle stop function, since stop/start of the engine is frequently performed and the use frequency of the starter is larger than that of the conventional starter, remedial measures for the above-described problems are required.
For this reason, a technology which prevents generation of an aperture between a point of action of the electromagnetic device and the clutch mechanism and the backlash of the clutch mechanism to prevent generation of noises is proposed. For example, a starter in which a gear plunger of an electromagnetic device is configured of an inner plunger, an outer plunger and a plunger spring is proposed.
The inner plunger is fitted onto the drive shaft and is configured to be slidable along the drive shaft. The outer plunger is installed outside in the radial direction of the inner plunger and concentrically with the inner plunger, and interlocked with the inner plunger so as to be slidable along the drive shaft. The plunger spring is installed between the inner plunger and the outer plunger.
According to the above-described starter, the outer plunger slides by supplying electricity to the exciting coil, and thus the inner plunger slides. Accordingly, the plunger spring may function as a backlash absorption mechanism configured to prevent backlash (for example, see Japanese Unexamined Patent Application, First Publication No. 2013-137014).
In the above-described 2-shaft type starter, the drive shaft and the idle shaft are disposed in parallel. For this reason, when the starter is assembled, two shafts should be assembled, the drive shaft of a first side is supported by the base plate and the gear cover and the idle shaft of a second side are supported by the gear cover at both ends sides thereof. For this reason, after the drive shaft and the pinion are installed on the gear cover, the idle shaft should be installed on the gear cover such that the idle gear is held while meshed with the pinion, and thus the time need to fabricate the starter may increase.
Here, while the structure in which the gear cover is divided into two members in the axial direction of the drive shaft has been proposed, when the two shafts are sandwiched between the two members, respective parts are assembled in the gear cover such that a worker cannot see the parts from the outside. For this reason, the work of positioning the shafts and meshing the gears may become difficult.
In addition, since the driving pinion gear and the ring gear are helically meshed, upon start the engine, the direction of the thrust load generated from the driving pinion gear varies based on the rotational speed difference between the driving pinion gear and the ring gear. Specifically, it varies such that the starting is started and the ring gear is driven by the driving pinion gear of the starter side, the rotational speed of the ring gear is lower than that of the driving pinion gear, and, as described above, the thrust load to the ring gear in the plunge direction is generated from the driving pinion gear.
On the other hand, when the engine is started by the starter, the rotational speed of the ring gear is increased depending on an increase in rotating speed of the engine. As a result, when the rotational speed of the ring gear is higher than that of the driving pinion gear, a thrust load is applied to the driving pinion gear in a direction separated from the ring gear (an opposite direction of the plunge direction). Here, when the weight of the driving pinion gear is large, the generated thrust load may be equal to or larger than a holding force (an attractive force) by an electromagnet of an electromagnetic switch. Then, the driving pinion gear cannot be held at a position meshing with the ring gear, and the driving pinion gear may be separated from the ring gear before the engine is completely started.
In addition, before and after the piston of the engine passes through a top dead point and a bottom dead point, the rotational speed of a crankshaft of the engine is varied by a compressive force of a fuel-air mixture and an explosive force of fuel in a combustion chamber. Since the ring gear is integrally formed with the crankshaft, the rotational speed of the ring gear varies along with the crankshaft. Accordingly, the thrust load generated in the driving pinion gear is temporarily equal to or larger than the holding force by the electromagnetic switch, and the driving pinion gear may also be separated from the ring gear before the engine is completely started.
Further, the driving pinion gear may also be separated from the ring gear, and the member such as the shaft integrally installed on the driving pinion gear or the driving pinion gear may collide with the stopper or the like configured to restrict a movement thereof, generating abnormal noises.
In order to cope with the above-described phenomenon, the electromagnetic force of the electromagnetic switch may be increased, but it is not preferable because the weight, the size, and so on, of the coil of the electromagnetic switch are increased.
In addition, since the driving pinion gear separated from the ring gear plunges into the ring gear again while the starter is driven, an abutting sound may be generated between the ring gear and the driving pinion gear each time and cause abnormal noises.
Here, as the magnetic holding force of the gear plunger is increased, simply increasing the magnetic force of the electromagnetic device to increase the holding force of the gear plunger by the exciting coil in order to retain a separating force applied to the driving pinion gear from the ring gear may be considered.
However, when the magnetic force of the electromagnetic device is simply increased, the electromagnetic device may also be increased in size and thus the starter may also be increased in size, exerting an influence on a vehicle mounting property of the starter.
In addition, in the above-described related art, in the assembly state of the oil seal 506, as shown in FIG. 42, a gap S100 is generated between the oil seal 506 and the inner flange section 507. Then, a foreign substance such as water or the like may remain in the gap S100. When the foreign substance is moisture, the water may corrode the shaft 502, or may freeze and cause poor sliding between the shaft 502 and the oil seal 506.
In addition, as described above, before electricity supplied to the electromagnetic device is cut, the pinion gear may fall out of the ring gear due to the thrust load applied to the pinion gear toward the opposite side of the ring gear. In this case, since the electromagnetic device is still supplied with electricity, the pinion gear plunges into the ring gear again, ultimately causing abnormal noises.